1. Field of the Invention
The present invention relates to movable body driving methods and movable body drive systems, patterning methods and apparatus, exposure methods and apparatus, position control methods and position control systems, and device manufacturing methods, and more particularly, to a movable body drive method and a movable body drive system in which a movable body is driven along a predetermined plane, a pattern formation method using the movable body drive method and a pattern formation apparatus equipped with the movable body drive system, an exposure method using the movable body drive method and an exposure apparatus equipped with the movable body drive system, a position control method and a position control system to control the position of the movable body, and a device manufacturing method using the pattern formation method.
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing microdevices (electron devices and the like) such as semiconductor devices and liquid crystal display devices, exposure apparatuses such as a projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner) are relatively frequently used.
In this kind of exposure apparatus, in order to transfer a pattern of a reticle (or a mask) on a plurality of shot areas on a substrate such as a wafer or a glass plate (hereinafter, generally referred to as a wafer), a wafer stage holding the wafer is driven in a two-dimensional direction, for example, by linear motors and the like. Position measurement of the wafer stage and the like was generally performed using a laser interferometer whose stability of measurement values was good for over a long time and had a high resolution.
However, requirements for a stage position control with higher precision are increasing due to finer patterns that accompany higher integration of semiconductor devices, and now, short-term variation of measurement values due to temperature fluctuation of the atmosphere on the beam path of the laser interferometer or the influence of temperature gradient has come to occupy a large percentage in the overlay budget.
Meanwhile, as a measurement device besides the laser interferometer used for position measurement of the stage, an encoder can be used, however, because the encoder uses a scale, which lacks in mechanical long-term stability (drift of grating pitch, fixed position drift, thermal expansion and the like), it makes the encoder have a drawback of lacking measurement value linearity and being inferior in long-term stability when compared with the laser interferometer.
In view of the drawbacks of the laser interferometer and the encoder described above, various proposals are being made (refer to Kokai (Japanese Patent Unexamined Application Publication) No. 2002-151405 bulletin) of a device that measures the position of a stage using both a laser interferometer and an encoder (a position detection sensor which uses a diffraction grating) together.
Further, the measurement resolution of the conventional encoder was inferior when compared with an interferometer. However, recently, an encoder which has a nearly equal or a better measurement resolution than a laser interferometer has appeared (for example, refer to Kokai (Japanese Patent Unexamined Application Publication) No. 2005-308592 bulletin), and the technology to put the laser interferometer and the encoder described above together is beginning to gather attention.
For example, in the exposure apparatus, in the case of performing position measurement of a wafer stage on which a scale (a grating) has been arranged using an encoder, in order to cover a broad movement range of the wafer stage, it is conceivable that a plurality of heads are placed at a predetermined interval within a two-dimensional plane. However, in the case of using the plurality of heads having such a placement, because the scale is placed on the upper surface of the wafer stage, for example, foreign materials such as particles can easily adhere to the surface of the scale, and in the case such foreign particles adhere to the scale, position measurement accuracy of the wafer stage by an encoder deteriorates, or position measurement becomes difficult. Accordingly, when the position control of the wafer stage is performed using an encoder, it is desirable to prepare a countermeasure of some kind which takes such a situation into consideration.